Everything You Need To Know About Porcelain Clay

The ultimate success of a ceramics project is defined by the quality of the raw materials used.  An unsuitable type of clay for a project can lead to erroneous results. The 3 predominant types of clay used in pottery and ceramics are Porcelain Clay, Earthenware Clay and Stoneware Clay. All hold unique properties suited to different end goals.

Many of the most skilled potters prefer working with porcelain clay, and here we explain the differences between the different types of clay and why the properties of porcelain clay often elevate it above the others.

What is Porcelain Clay?

Porcelain clay is perhaps the most renowned form of clay for creating delicate objects such as fine bone china or figurines. In its raw state, it is typically white or gray in color. It is also very soft in texture and more flexible or ‘plastic’ than the other kinds of clay.

Due to its delicate, soft nature, it is not easy to shape and requires moisture throughout the shaping process. Without enough water, porcelain can quickly dry out and if you add too much water it can easily lose its shape and collapse. Porcelain clay was used for the creation of some of the most highly valued antique figures.

What is Stoneware Clay?

Stoneware clay is considered the most versatile and easiest clay to work with and is an ideal material for those who have yet to develop the necessary skills to make finer pieces. It can be bought in a variety of colors from white to dark brown. Once fired, pottery made out of stoneware clay is very durable, strong and non-porous, which means it will be capable of holding liquid without having to glaze it.

Stoneware clay is a multi-purpose clay, used to make anything from small plates to big vases. It can be formed both on a pottery wheel or hand-crafted.

What is Earthenware Clay?

Earthenware clay is most commonly known for its use as terracotta, often used to make flower pots and tiles. It tends to be thicker and heavier, but weaker than stoneware. Earthenware clay is porous, which means that it is not suitable for holding any liquids, unless glazed several times.

Why do potters choose porcelain clay over other types of clay?

Porcelain clay is known as the ‘regal’ of all clay types. Although it is renowned as being more difficult to work with than other clay materials, it is its makeup of very fine materials that makes it perfect for sculpting delicate patterns, such as highly decorative figurines and creating realistic lifelike pleating in clothing etc.

Porcelain clay is also highly durable and less porous than other clay types and so has longevity if used to create a food or beverage holder.

It may seem strange, but some potters like working with porcelain clay because it is less forgiving. It forces them to throw faster before the clay breaks down. The fine minerals used to  form the clay are smaller than those found in other clay types, which makes it that much harder to form on the pottery wheel, and so requires a skilled hand.

However, what makes porcelain more challenging to throw than other clay types also makes it more versatile. Because porcelain clay uses such fine material, it can feel very smooth on the potter's wheel, allowing more intricate manipulation. Making thin or delicate shapes out of stoneware or earthenware will ultimately lead to them collapsing but this is not the case with porcelain clay.

As potters become more skilled, porcelain clay provides them with the challenge to create ever more intricate detail and push the limits of their skills. Porcelain clay reduces the boundaries of what can be created out of clay and enables creators to sculpt the most decorative, skilled and accomplished pieces and in turn a higher sell on value.

Is porcelain clay natural or does it need to be manufactured?

Unlike other types of clay, the creation of porcelain clay requires a more complex process. Porcelain clay is formed by mixing ball clay or china clay with a variety of materials and additives to form its unique properties. Most porcelain clays contain kaolin, which comes from the mineral kaolinite, a naturally mined substance that can be found in many different countries across the world. This gives porcelain clay its white/gray coloration.

The component parts are crushed to an extremely fine powder and then mixed to form the correct consistency and color.

What makes porcelain clay unique?

The major difference between porcelain and other clays is the composition. Other types of clay are made mostly of natural clay, with a few additional organic materials and water, while porcelain pieces instead have a light mix of clay, kaolin, silica, quartz, feldspar and various other materials, to create a very smooth finished clay. Because of this, porcelain is denser, less porous, finer, durable, and more translucent than other pottery clays. It also has high plasticity, which makes it much easier to manipulate into intricate objects.

Compared with other forms of clay, porcelain clay can be fired at high temperature, so the clay body is firmer and has higher hardness and durability. This allows it to be crafted with a much thinner and more delicate finish. Porcelain clay also has almost no water absorption, so the finished product is long lasting.

Is porcelain clay more expensive than earthenware and stoneware clay?

The simple answer to this question is yes. Porcelain clay gives the most translucent and durable finish, water resistance and also enables the creation of the finest and most valuable pieces of china. It is also made of a combination of several materials to form its unique properties, which adds to the expense of manufacture.

Porcelain clay is fired to a higher temperature than earthenware and stoneware. The raw materials required to resist this heat exposure are more expensive and therefore in combination add up to a more expensive finished product.

As a higher quality material, producing a high quality output, it is perhaps inevitable that porcelain clay is the most expensive clay type to buy.

In summary

Why do potters choose porcelain clay over earthenware clay and stoneware clay? Put simply, it is the quality of the finished product that can be created. A finished porcelain piece can be created with more detail, is more durable, provides a smooth, translucent finish and offers non-porous properties. A truly ‘regal’ raw material!

We welcome any questions or queries you may have and are happy to give the advice that you need, whether you are a hobbyist or you use clay as part of your business venture.

Additional resources on pottery

• Pottery Wheel Throwing Tips & Techniques
• A Guide To China Paint Materials, Techniques and Firing
• How and Why Slow Firing Porcelain Produces Better Results